APPENDIX B. 



121 



I am desirous of adding a few remarks on "■ Sparvius 

 gilvicollis" of Vieillot, " Nisus concentricus" of Lesson, and 

 " Micrastur pelzelni" of Ridgway. 



Messrs. Salvin and Godraan, in the P. Z. S. for 1869, p. 368, 

 have, on the authority of Pucheran, admitted the identity of 

 the two first {conf. Rev. et Mag. de Zoologie, 1850, p. 91). 

 It seems to me that Pucheran was probably correct in this 

 identification, that "Nisus concentricus" of Lesson is founded 

 on the immature or partially immature plumage of the same 

 species as that which, in its fully adult dress, received from 

 Vieillot the designation of "Sparvius fjilvicoUis ," and that in 

 this adult stage it is not separable from Micrastur pelzelni of 

 Ridgway. 



Mr. Ridgway, in his monograph of the genus Micrastur, 

 to which I have already referred, writes thus under the head 

 of M. pelzelni : — " In abbreviated tail it is like M. concentricus 

 .... but it differs very essentially in the relative length of 

 the lateral toes, the outer one being decidedly longer than 

 the inner, instead of being barely equal to it or appreciably 

 shorter, while the barred crissum and under wing-coverts 

 distinguish it at a glance from that species. '^ And again, 

 writing of M. concentricus, he remarks : — " This very distinct 

 species may be immediately distinguished by the peculiar 

 proportions of the lateral toes and by having the tail shorter 

 than the wing ; while in its adult dress it is unique in the 

 white throat and unbarred crissum and anal region, as well 

 as by the yellowish instead of dusky colour of the bill, though 

 we are not sure of the constancy of the latter feature." 



My own belief is that all these peculiarities of colouring 

 indicate immaturity rather than the reverse, except perhaps 

 the white throat, which, as also the slight differences in the 



